Date: Fri, 10 Aug 2018 14:44:26 -0400 From: Mark Johnston <markj@freebsd.org> To: Bruce Evans <brde@optusnet.com.au> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r337426 - head/sbin/ifconfig Message-ID: <20180810184426.GB52302@raichu> In-Reply-To: <20180810092251.K1276@besplex.bde.org> References: <201808071725.w77HPciT051597@repo.freebsd.org> <20180810092251.K1276@besplex.bde.org>
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On Fri, Aug 10, 2018 at 10:25:50AM +1000, Bruce Evans wrote: > On Tue, 7 Aug 2018, Mark Johnston wrote: > > > Log: > > ifconfig: Fix use of _Noreturn. > > > > The _Noreturn is a function-specifier (like inline) which must preceed > > the declarator. > > > > Submitted by: Sebastian Huber <sebastian.huber@embedded-brains.de> > > MFC after: 1 week > > _Noreturn is even more broken than I knew. It should never be used. Here > its use is wronger than usual. > > > Modified: head/sbin/ifconfig/ifconfig.c > > ============================================================================== > > --- head/sbin/ifconfig/ifconfig.c Tue Aug 7 17:13:42 2018 (r337425) > > +++ head/sbin/ifconfig/ifconfig.c Tue Aug 7 17:25:38 2018 (r337426) > > @@ -109,7 +109,7 @@ static int ifconfig(int argc, char *const *argv, int i > > static void status(const struct afswtch *afp, const struct sockaddr_dl *sdl, > > struct ifaddrs *ifa); > > static void tunnel_status(int s); > > -static void usage(void) _Noreturn; > > +static _Noreturn void usage(void); > > > > static struct afswtch *af_getbyname(const char *name); > > static struct afswtch *af_getbyfamily(int af); > > FreeBSD code should use __dead2 since it is more portable (within > FreeBSD) and doesn't have so mean syntactical restrictions. However, > it only exists at all since it had similar syntactial restrictions > when it was new (FreeBSD-1 used __dead, which must be placed like > _Noreturn, but __dead2 uses __attribute__(()) which couldn't be placed > there when it was new), and the macro that hides the details was renamed > to inhibit misuse. Changing __dead2 to _Noreturn and moving it to satisfy > the restricted syntax of the latter mainly broke support for old compilers > where __dead2 cannot be placed there. __dead2 was never present. _Noreturn was added in r317755, apparently to appease Coverity. > However, all declarations of static usage() as non-returning are bogus, ... I can only agree, especially since exit() is already declared with _Noreturn in stdlib.h. I don't understand why __dead2/_Noreturn keeps getting added to various usage() declarations.
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